Linux Ethernet Bridging - Jul 2015 - [Bridge] [PATCH net-next] bridge: mcast: when multicast is disabled flush the groups

From: Satish Ashok <sashok at cumulusnetworks.com>

Once multicast gets disabled we should flush the groups.
Example:
# bridge mdb add dev br0 port eth3 grp 239.0.0.1
# bridge mdb
dev br0 port eth3 grp 239.0.0.1 temp
# echo 0 > multicast_snooping
# bridge mdb

Signed-off-by: Satish Ashok <sashok at cumulusnetworks.com>
Signed-off-by: Nikolay Aleksandrov <nikolay at cumulusnetworks.com>
---
 net/bridge/br_multicast.c | 17 ++++++++++++++++-
 1 file changed, 16 insertions(+), 1 deletion(-)

diff --git a/net/bridge/br_multicast.c b/net/bridge/br_multicast.c
index 0dd3cd90962c..cf79bfc16e30 100644
--- a/net/bridge/br_multicast.c
+++ b/net/bridge/br_multicast.c
@@ -39,6 +39,7 @@ static void br_multicast_start_querier(struct net_bridge *br,
 				       struct bridge_mcast_own_query *query);
 static void br_multicast_add_router(struct net_bridge *br,
 				    struct net_bridge_port *port);
+static void br_multicast_del_grps(struct net_bridge *br);
 unsigned int br_mdb_rehash_seq;
 
 static inline int br_ip_equal(const struct br_ip *a, const struct br_ip *b)
@@ -553,6 +554,7 @@ static struct net_bridge_mdb_entry *br_multicast_get_group(
 			err = -E2BIG;
 disable:
 			br->multicast_disabled = 1;
+			br_multicast_del_grps(br);
 			goto err;
 		}
 	}
@@ -1866,6 +1868,17 @@ static void br_multicast_start_querier(struct net_bridge
*br,
 	}
 }
 
+static void br_multicast_del_grps(struct net_bridge *br)
+{
+	struct net_bridge_port *port, *bn;
+	struct net_bridge_port_group *pg;
+	struct hlist_node *n;
+
+	list_for_each_entry_safe(port, bn, &br->port_list, list)
+		hlist_for_each_entry_safe(pg, n, &port->mglist, mglist)
+			br_multicast_del_pg(br, pg);
+}
+
 int br_multicast_toggle(struct net_bridge *br, unsigned long val)
 {
 	int err = 0;
@@ -1876,8 +1889,10 @@ int br_multicast_toggle(struct net_bridge *br, unsigned
long val)
 		goto unlock;
 
 	br->multicast_disabled = !val;
-	if (br->multicast_disabled)
+	if (br->multicast_disabled) {
+		br_multicast_del_grps(br);
 		goto unlock;
+	}
 
 	if (!netif_running(br->dev))
 		goto unlock;
-- 
2.4.3

On Wed, Jul 22, 2015 at 3:28 AM, Nikolay Aleksandrov
<nikolay at cumulusnetworks.com> wrote:
> From: Satish Ashok <sashok at cumulusnetworks.com>
>
> Once multicast gets disabled we should flush the groups.
> Example:
> # bridge mdb add dev br0 port eth3 grp 239.0.0.1
> # bridge mdb
> dev br0 port eth3 grp 239.0.0.1 temp
> # echo 0 > multicast_snooping
> # bridge mdb
Why? Why we can't save the mdb config for a mcast snooping flip?